Production of wax heaters

ABSTRACT

WAX FILLED HEATERS ARE PRODUCED BY HOMOGENIZING SOLID SLACK WAX AND FILLING A CONTAINER WITH HOMOGENIZED SLACK WAX.

United States Patent US. CI. 44-40 5 Claims ABSTRACT OF THE DISCLOSUREWax filled heaters are produced by homogenizing solid slack wax andfilling a container with homogenized slack wax.

This invention relates to a process for the production of wax heaters.

Our copending application, BP Case DNL.2681 discloses an orchard heatercomprising a container containing a wax composition, the sides of thecontainer being formed of a flame-retardant material the rate ofcombustion of which is lower than that of the wax composition, the baseof the container being formed of a combustible material.

British patent specification 1,126,014 discloses an article ofmanufacture comprising a fire-resistant container having an open end anda heating composition consisting essentially of 90-99.9% by weight of awax component containing 01-10% by weight of a buoyant particulatematerial component in contact with the wax in the container.

Up to the present, such heaters have been prepared by pouring hot moltenWax into a container and allowing the wax to cool. Unfortunately, waxshrinks on cooling and thus the container must be topped up with morewax in a second stage operation, with a lengthy cooling periodintervening. A further problem is involved if the material known asslack wax is employed. Slack wax is a by-product obtained in themanufacture of lubricating oils and asphalts. It comprises a mixture ofparafiin wax and normally liquid hydrocarbons. When poured hot andallowed to cool it tends to separate into a solid or semisolid phase anda liquid phase. Furthermore if containers are to be filled with moltenwax, they must be made stronger than is necessary to hold the wax whenit is solidified. When the wax heater is lit only a small proportion ofthe wax is molten so that the greatest strain on the container is whenmolten wax is used to fill it. i

We have now discovered a process which enables containers to be filledby slack wax without the use of molten Wax in a one-stage operationWithout cooling, shrinking or phase separation problems arising.

Thus according to the present invention there is provided a process forthe production of Wax filled heaters which process compriseshomogenizing solid slack wax and filling a container with thehomogenized slack wax composition.

The homogenization of the slack wax is achieved by mechanically workingthe solid slack wax. This mechanical working converts the solid wax intoa product which has some of the properties of a viscous liquid in thatit can flow to take up the shape of a container into which it is poured,even though the mechanically worked wax is at ambient temperatures. Themechanical working converts the wax into a fluid with non-Newtonian flowproperties. The homogenization may be achieved by any convenient methodof mechanically working the wax. Thus 3,782,910 Patented Jan. 1, 1974cold slack wax may be milled in a pug mill, or it may be introduced intospecial pumps capable of handling very viscous materials. Alternatively,homogenization may be achieved by the use of shear or extrusionhomogenizers.

The container into which the homogenized wax is introduced may have aside wall of a flame-retardant material, e.g. card covered withaluminium foil, the rate of combustion of which is lower than that ofthe wax composition, the base of the container being formed of acombustible material e.g. plastics material as disclosed in copendingapplication, Case DNL.2681. The use of the process of the presentinvention avoids the problems of shrinkage and phase separation referredto above. Furthermore the possible hazards of having to handlecontainers full of hot wax, and the problems of finding space to storethe heaters until the wax is cool, are avoided.

The invention will now be illustrated by reference to the accompanyingexamples.

EXAMPLE 1 Hot slack wax from a storage tank was passed to the surface ofa rotary cooling drum from which the cooled solid wax was removed by ascraper. It was then fed to a solids pump, which was a Comet 4 inchheavy duty positive displacement pump modified to have a 5 inch inlet,and pumped through a tube into cardboard containers covered withaluminium foil. Despite the fact that the Wax was well below its meltingpoint, the containers were satisfactorily filled in a uniform manner. Noshrinkage of the Wax and no separation of wax and oil occurred. Thefilled containers could be immediately fitted with lids and removed fromthe vicinity of the filling plant for storage. Similar results wereobtained by extruding wax using a pug-mill with a perforated plate andtransporting the resulting semi-liquid product to fill the containersusing any one of a variety of positive displacement pumps e.g. a MirrlesTirro rotary screw positive displacement pump V 338:.

EXAMPLE 2 This is a comparative example not according to the invention.Containers of the type used in Example 1 were filled with molten slackwax. It was found necessary to allow the containers to stand for 8 hoursto allow the wax to cool and solidify. It was then necessary to addfurther quantities of molten wax to the containers to make up forshrinkage, and to allow the containers to cool down over a further 8hour period before the containers could be stacked on pallets. It wasobserved that the molten wax caused the board from which the containerswere made to soften so that thicker walls are required using molten waxif the container is to have adequate strength during filling. It will berealized that in addition to the economic penalty of having to providestronger containers when using molten wax, there will be additionalcosts arising from the extra handling of the container needed because ofthe topping up of the container with molten wax required to compensatefor shrinkage in the wax originally added. Furthermore the filling areamust be very large to allow the containers containing molten wax to beset out for cooling before they can be removed for storage. If themolten wax filling plant is operated during the day only, the productionon the first day will not be ready for topping-up with further moltenWax till the second day, and will not be ready for removal to storagetill the third day. Floor space for storing 3 days production of waxfilled containers in the filling area is therefore required.

I claim:

1. A process for the production of wax filled heaters which compriseshomogenizing solid slack wax and filling a container with thehomogenized slack wax composition at ambient temperatures.

2. A process according to claim 1 wherein the slack wax is homogenizedby being mechanically worked in a pump.

3. A process according to claim 1 wherein the slack wax is homogenizedby being mechanically worked in a 10 pug mill.

4. A process according to claim 1 wherein the container into which thewax is filled has a side wall of flame-retardant material, and a base ofcombustion material.

5. A process according to claim 4 wherein the container comprises a sidewall of card covered with aluminium foil and a base of plasticsmaterial.

References Cited UNITED STATES PATENTS Van Tassel, Jr 241-30 Hopkins241-30 Voorhees 106270 Schiermeier et a1. 20821 X Olson 20821 X Bel-aket al. 44-40 X Ambrose et a1 4440 Hicks 44--7.5 X

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION BP 3049 Patent No.782 910 Dated January 1 1974 lnventoflw EDWARD BARNES It is certifiedthat error appears in the above-identified patent and that said LettersPatent arehereby corrected as shown below:

Claim 4, line 3, thereof, change "combustion" to --combustible-.

Signed and sealed this 9th day of A r-i 19m.

(SEA Attest:

' EDWARD DLFLETCHERJR. 0. MARSHALL DANN Atte sting Officer Commissionerof Patents i

